1. Field of the Invention:
The invention is in the field of ultrasonic imaging.
2. Description of the Prior Art.
Ultrasonic transmission imaging and ultrasonic reflection imaging have been utilized for visualization of the interior of biological specimens in the prior art. The primary use has been made of ultrasonic reflection imaging, which inherently provides focused transmission and reception when a focused transducer is utilized.
It has been reported that ultrasonic transmission images possess several advantages over ultrasonic reflection images. Although earlier transmission imaging showed encouraging results, transmission imaging was soon replaced by reflection imaging because of the technological difficulties of transmission imaging and because of problems associated with the passage of ultrasonic energy through the entire body of a subject. However, with the advent of the technology, transmission ultrasonography is currently being reinvestigated and several such systems have been reported.
So far as applicants are aware, transmission ultrasonography has not been utilized employing focused transmitting and receiving transducers. In addition, so far as applicants are aware, neither ultrasonic transmission imaging nor reflection imaging has utilized random frequency noncoherent ultrasound of the imaging.